A malocclusion is a misalignment of teeth or incorrect relation between the teeth of the two dental arches. The term was coined by Edward Angle—the father of modern orthodontics—as a derivative of occlusion, which refers to the way opposing teeth meet. Angle based his classifications of malocclusions on the relative position of the maxillary first molar. According to Angle, the mesiobuccal cusp of the upper first molar should align with the buccal groove of the mandibular first molar. The teeth should all fit on a line of occlusion, which is a smooth curve through the central fossae and cingulum of the upper canines, and through the buccal cusp and incisal edges of the mandible. Any variations therefrom is a malocclusion.
There are three classes of malocclusions, Class I, II, and III. Further, class II is subdivided into three subtypes:
Class I: Neutrocclusion The molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have other problems like spacing, crowding, over or under eruption, etc.
Class II: Distocclusion (retrognathism, overjet) In this situation, the upper molars are placed not in the mesiobuccal groove, but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. There are two subtypes:
Class II Division 1: The molar relationships are like that of Class II and the anterior teeth are protruded.
Class II Division 2: The molar relationships are class II, but the central incisors are retroclined and the lateral incisors are seen overlapping the central incisors.
Class III: Mesiocclusion (prognathism, negative overjet) In class III mesiocclusions the upper molars are placed not in the mesiobuccal groove, but posteriorly to it. The mesiobuccal cusp of the maxillary first molar lies posteriorly to the mesiobuccal groove of the mandibular first molar. This malocclusion is usually seen when the lower front teeth are more prominent than the upper front teeth. In such cases, the patient very often has either a large mandible or a short maxillary bone.
Orthodontics, formerly orthodontia (from Greek orthos “straight or proper or perfect” and odous “tooth”), is the first specialty of dentistry that is concerned with the study and treatment of malocclusion, which can be a result of tooth irregularity, disproportionate facial skeleton relationship, or both. Orthodontics treats malocclusion through the displacement of teeth via bony remodeling and control and modification of facial growth.
This process has been accomplished for thousands of years using static mechanical force to induce bone remodeling, thereby enabling teeth to move. In fact, archaeologists have unearthed ancient mummies that have crudely constructed bands of metal around their teeth.
In modern orthodontics, braces consisting of an archwire interfaces with brackets that are affixed to each tooth. As the teeth respond to the pressure applied via the archwire by shifting their positions, the wires are again tightened to apply additional pressure. This widely accepted approach to treating malocclusion takes about twenty-four months on average to complete, and is used to treat a number of different classifications of clinical malocclusion.
Treatment with braces is complicated by the fact that it is uncomfortable and/or painful for patients, and the orthodontic appliances are perceived as unaesthetic, all of which creates considerable resistance to use. Additionally, the 2 year treatment time is very long and cannot be shortened by increasing the force, since too high a force is both painful and leads to tooth resorption. In fact, some estimates provide that less than half of the patients who could benefit from such treatment elect to pursue orthodontics.
Kesling introduced the tooth positioning appliance in 1945 as a method of refining the final stage of orthodontic finishing after removal of the braces (debanding). The positioner was a one-piece pliable rubber appliance fabricated on the idealized wax set-ups for patients whose basic treatment was complete.
Kesling also predicted that certain major tooth movements could also be accomplished with a series of positioners fabricated from sequential tooth movements on the set-up as the treatment progressed. However, this idea did not become practical until the advent of 3D scanning and computer modeling in 1997, when the Invisalign® system was introduced by Align Technologies®.
In addition to static forces, cyclic forces can also be used for orthodontic remodeling. Kopher and Mao assessed cyclic forces of 5N peak magnitude at 1 Hz in rabbits, while Peptan and Mao assessed cyclic forces of 1N at 8 Hz in rabbits, and Vij and Mao assessed cyclic forces of 300 mN at 4 Hz in rats. In aggregate, the data from these three studies indicated that cyclic forces between 1 Hz and 8 Hz, with forces ranging from 0.3N to 5N, increased bone remodeling. Rates depended on different methodologies, but increases of up to 2.5× with vibrational forces were common.
Since Dr. Mao's experiments, an independent study out of Japan has confirmed and strengthened the idea of vibration at 60 Hz for speeding orthodontic tooth movement, and an earlier 50 Hz study in Russia also confirms the basic premise. In fact, by now there is a well established literature confirming the efficacy of this treatment modality.
The early Mao studies provided a basis for both possible efficacy and likely safety for using vibration in humans to assist orthodontic tooth movement, but the animal studies needed to be repeatable in humans, and the devices used by Mao and the others were completely unsuitable for clinical work.
OrthoAccel® Technologies Inc., invented the first commercially successful dental vibrating device, as described in US2008227046 and related cases, designed to apply cyclic forces to the dentition for accelerated remodeling purposes. Both intra-oral and extraoral embodiments are described in US2008227046, each having processors to capture and transmit patient usage information.
The bite plate was specially designed to contact occlusal as well as lingual and/or facial surfaces of the dentition, and thus was more effective than any prior art devices in conveying vibrational forces to the teeth. Further, the device was tested in clinical trials and has been shown to speed orthodontic remodeling as much as 50%, and is truly a breakthrough in orthodontic technology (Kau 2010).
Finally, the device is slim, capable of hands free operation, lacks the bulky head gear of the prior art devices, and has optimized force and frequency for orthodontic remodeling. Thus, its comfort level and compliance was also found to be high, with patients reporting that they liked the device, especially after the motor was redesigned to be quieter and smoother, as described in US2010055634 et seq. In fact, this device has been marketed as AcceleDent® in the United States, and several other countries and has achieved remarkable commercial success since its recent introduction. AcceleDent® represents the first successful clinical approach to accelerate orthodontic tooth movement by modulating bone biology in a non-invasive and non-pharmacological manner.
Although compliance with the AcceleDent® is fairly good, with certain patients compliance is less than satisfactory. In investigating the basis for non-use, OrthoAccel® discovered that a poorly fitting bite plate reduced compliance because the extraoral vibratory source, coupled with a poorly fitting bite plate, resulted in excessive salivation, which tended to egress from the oral cavity. Patients with poorly fitting bite plates were more likely to have poor compliance records. In addition, the original bite plate was shaped to fit the classic “Euro arch” which is narrower in form than many Asian arches. Thus, the original devices tend to fit the Asian patient, or patients with the Damon arch (an even wider arch form) less well.
WO2011056260 attempted to solve this problem with a series of bite plates in a small, medium and large size together with open, flat and deep bite plate architecture, thus providing a series of 9 bite plates that fit a significant percentage of the population. While this solution is one viable option, it requires tooling up and inventory for a substantial number of bite plates, and further still is less than a perfect solution for the wider arches, since it was still based on the Euro arch.
Another option is to make the bite plate with a shapeable material, such as the boil and bite mouth guards. U.S. application Ser. No. 13/967,043, filed Aug. 14, 2013 describes a bite plate having a bead of light curable resin thereon, which can be shaped once by the patient, and then uv light cured in the orthodontic office. This option, however, requires that inventory be protected from light, and long term stability might be an issue. Further, once shaped it cannot be reshaped, therefore as treatment progresses new bite plates will be needed.
Custom dental appliances are, of course, readily available, as indicated by the aligner and positioner markets. However, these products require 3D modeling and/or custom impressions made of the dentition and some time in an offsite laboratory facility to make the custom fitted appliance. Alternatively, the practitioner can make his own devices, e.g., with a 3D printer, but again lab time is needed, thus contributing to inefficiencies.
Therefore, what is needed in the art is a shapeable bite plate that can be individually fitted to each patient, without a significant time investment needed by the patient or practitioner, and without a significant inventory commitment by distributors. This application addresses some of those needed improvements.